1. Technical Field
The present invention relates to an adapter seal for use with a cannula assembly of a trocar and to a method for performing surgical procedures using the adapter seal.
2. Description of the Prior Art
Endoscopic and laparoscopic surgical procedures are often performed with an insufflatory gas present within the body cavity being accessed to provide an operative field for the surgeon. Insufflatory surgery is generally performed by puncturing the body wall in the region of the desired body cavity with a pneumoperitoneum needle, e.g., a Verres needle. The needle includes a hollow stylet through which insufflatory gas may be introduced to the body cavity.
A trocar assembly may then be used to provide a port of entry into the body cavity for introduction of endoscopic surgical instruments, e.g., graspers, dissectors, scopes, clip appliers, stapling devices, and the like. These instruments have differing sizes, for example, some instruments have a cross-sectional diameter in their elongate sections on the order of 5 mm whereas others have a diameter of 10 mm or larger. The trocar assembly for creating the port of entry includes an obturator assembly which generally includes a piercing tip at the distal end of an obturator and an obturator housing, and a cannula assembly which generally includes a tubular cannula or sleeve and a cannula housing. The obturator is adapted to be inserted through the cannula such that the piercing tip is exposed from the cannula at the distal end thereof. In this operative condition, the trocar housing and cannula housing generally assume a mating relationship.
In recognition of the variability in instrument diameters, cannulas are available with different inner diameters. Commercially available trocar assemblies offer cannulas having a broad range of inner diameters, ranging from 3 to 15 mms (e.g., 3, 5, 7, 8, 10, 11, 12 and 15 mm sizes). After the body wall is penetrated by the piercing tip, the obturator assembly is generally separated from the cannula assembly, leaving the cannula extending into the body cavity for receipt of surgical instrumentation, as described above.
In order to maintain the insufflatory gas within the body cavity, thereby maintaining the surgeon's operative field, a cannula housing is generally provided with a seal system that is designed to provide a substantial fluid-tight seal in the absence of a surgical instrument positioned therethrough, and to sealingly engage a surgical instrument inserted therethrough. Thus, for example, a trocar assembly which is nominally designated a "10 mm trocar" would generally include a cannula having an internal diameter sufficiently greater than 10 mm to accommodate 10 mm instruments, and a cannula housing that included a seal system adapted to provide a fluid-tight seal in the absence of a surgical instrument and to sealingly engage instruments of 10 mm diameter. More recently, cannula housings have been provided with seal systems that are designed to sealingly engage surgical instrumentation across a range of instrument diameters, e.g., 10 to 12 mm, 4 to 5 mm, etc. Such flexibility is desirable because, with the advent and increased acceptance of additional minimally invasive surgical procedures, surgeons desire to utilize instruments of varying diameters in surgical procedures while maintaining the number of cannula assemblies to a minimum.
U.S. Pat. Nos. 4,601,710 to Moll and 4,654,030 to Moll et al. disclose trocar assemblies which include an elongate trocar obturator having a piercing tip at its front end and an elongate trocar tube or cannula in which the trocar obturator is housed. As shown in the '030 patent, a flapper valve may be employed to close off the cannula passage after the trocar obturator or other instrument has been withdrawn.
A gasket may also be employed to ensure a seal between the trocar assembly and an instrument inserted therein. U.S. Pat. No. 4,000,739 to Stevens, for example, teaches a hemostasis cannula having a pair of juxtaposed gaskets mounted in the passageway to the cannula, the first having a round hole and the second a Y-shaped slit. U.S. Pat. No. 3,994,287 to Turp et al. describes a trocar assembly which includes a flexible insulating ting received in a flange and a collar which retains the flexible ring in the flange. The flexible ting is allowed to flex as an instrument is inserted into the cannula and provides a seal with the instrument to prevent gas leakage. U.S. Pat. No. 4,112,932 to Chiulli describes a cannula which includes a turret member having first and second apertures. The turret member is movable such that a selected aperture is aligned with the bore of the cannula for passage of an instrument.
Trocar adapters and reducer sleeves which are adapted to be used in conjunction with a cannula assembly have also been provided for reducing or varying the size of the aperture for receipt of surgical instrumentation. U.S. Pat. No. 5,104,383 to Shichman describes an adapter seal which is adapted to be detachably associated with a cannula assembly to reduce the diameter of the aperture therethrough. The adapter seal is preferably provided with a stabilizer plate to limit the eccentric movement of an instrument relative to the seal.
Despite the availability of trocar assemblies having cannulas of various sizes and the availability of adapter seals and reducer sleeves for use in conjunction therewith, there remains a need for apparatus that may be used to vary the size of the aperture within a cannula assembly in a more efficient and efficacious manner.